This invention relates to an automatic ice making machine, more particularly to an automatic ice making machine having a measure which can effectively prevent accidents such as burning of compressor and waste of power or water to be frozen by giving an alarm externally at an early stage to notify presence of trouble whenever the normal ice making operation is hindered for some reasons.
Various types of automatic ice making machines for continually making various shapes of ice cakes including cube and plate in large quantities are utilized suitably depending on the applications. For example, popular ice making machines include:
(1) so-called closed cell system ice making machines having a multiplicity of freezing cells opening downward formed in a freezing chamber, in which the freezing cells can separably be closed with a water tray, and a water for freezing is injected into the freezing cells through the water tray to form ice cubes gradually therein; PA0 (2) so-called open cell system ice making machines having a multiplicity of freezing cells opening downward, in which a water to be frozen is directly injected into the freezing cells in the absence of the water tray to form ice cubes in the freezing cells; and PA0 (3) flow-down system ice making machines having a tilted freezing plate, in which a water to be frozen is supplied to flow on the upper or lower surface of the freezing plate to form an ice plate on the corresponding surface. PA0 (1) temperature detecting mode, in which a temperature element such as thermostat or thermistor disposed in the freezing chamber detects the temperature drop which occurs as the ice cakes grow to find the completion of ice cake formation; PA0 (2) water level detecting mode, in which a water level detector disposed in the water tank detects drop of the water level to a predetermined level after the water to be frozen is fed out therefrom with the growth of ice cakes to find the completion of ice cake formation; PA0 (3) pressure detecting mode, in which a pressure detector disposed on the discharge side of a circulating water pump detects the change in the discharge pressure of the pump to know the completion of ice cake formation; and PA0 (4) ice thickness detecting mode, in which an ice thickness detector disposed in the freezing chamber or on a freezing plate detects growth of the ice block to a predetermined thickness to know the completion of ice plate formation. PA0 (1) When a hot gas valve disposed in a hot gas circuit connecting the discharge side of the compressor and the evaporator is out of order to causes malfunction in the closing operation of the valve, the heated hot gas flows into the evaporator during the ice making operation to hinder the growth of ice cakes in the ice making section. In such occasion, the ice making mechanism is incapable of making ice cakes, so that the ice formation detector is not actuated to allow the ice making operation to continue without forming any ice cakes wasting power. Moreover, the above alarm unit never gives an alarm since it cannot detect such operational error. PA0 (2) When the water feed valve of the external water supply system is out of order to cause water leakage, the leaked water is also introduced to the water tank. Since the leaked water is of normal temperature, the entire water being cooled under circulation is subject to temperature rise when the amount of such leaked water is great to inhibit formation of ice cakes, and thus the ice making operation is likewise continued without forming any ice cakes, leading to the waste of power and water. On the other hand, if the amount of the leaked water is small, the ice cakes may grow but at a slow pace. In other words, the ice making operation time is extended to lower the freezing power, and increased amounts of power and water are consumed for making the same amount of ice cakes. However, the above alarm unit does not give an alarm in such occasions since it cannot detect such abnormal ice making operation. PA0 (3) When the ice formation detector is out of order, the ice making operation is continued even after ice cakes are formed to a full size. Accordingly, not only properly grown ice cakes cannot be secured but also an excessively large ice block grows in the ice making section. For example, the ice block grows to reach and damage the water feed system including the water tray, water sprinkling pipe and water tank. Nevertheless, the ice making operation is continued only to waste power.
These automatic ice making machines generally have an ice making mechanism in the upper part of the machine body and a freezing system for cooling said ice making mechanism at the lower part thereof, said freezing system comprising a compressor, a condenser, a capillary tube, an evaporator, etc.
The evaporator, a constituent of the freezing system, is disposed in the ice making section constituting the heart of the ice making mechanism and designed to cool the ice making section. A water to be frozen is circulably fed to the ice making section and frozen to form ice cakes. Upon detection of the growth of the ice to a predetermined size by an ice formation detector, feeding of the water to be frozen is stopped. Subsequently, by the selective operation of a valve, a heated gaseous cooling medium from the compressor is adapted to be fed through a bypass tube to the evaporator to heat the ice making section and allow the ice cakes formed therein to drop by their own weight, whereby the ice cakes thus released are collected and accumulated in a stocker disposed below the ice making section.
As the ice formation detector, various detection modes have conventionally been employed. For example:
In an automatic ice making machine in which any of the various types of ice making modes as described above can be employed, if clogging occurs, for example, in the condenser as the result of dust deposition on the radiator fins thereof, heat dissipation from the condenser is prevented to show reduced condensing power and require longer time for making ice cakes, whereby not only the freezing power is lowered but also the compressor is overheated to show reduced permanence, disadvantageously. For such reasons, the conventional automatic ice making machines have an alarm unit which gives a predetermined alarm when a temperature element such as thermistor disposed on the outlet pipe side of the condenser detects a temperature drop below a predetermined level.
As described above, in the conventional automatic ice making machine having a temperature element disposed on the outlet pipe side of the condenser, it is generally difficult to preset the actuation temperature for the temperature element and the following problems arise.
For example, at the initial stage of the ice making operation, the evaporator in the freezing system is subjected to high load for cooling a normal temperature water to be frozen supplied from the external water supply system, so that the condensation load is increased to elevate the temperature of the cooling medium on the discharge side of the condenser. After circulation of the cooling medium in the freezing system for some time, the water to be frozen is gradually cooled to have a lower temperature to require smaller load of the condenser, and in turn the temperature of the cooling medium from the outlet of the condenser is lowered. Thus, while the temperature of the cooling medium on the outlet side of the condenser is temporarily elevated at the early stage of ice making operation, the temperature element in the conventional automatic ice making machine even detects such temporary phenomenon and gives an alarm, disadvantageously. In other words, the alarm unit is actuated every time the ice making operation is initiated, and such alarm must be regarded as an error, since it is not attributable to essential abnormality such as trouble, and thus making the alarm system quite unreliable from the standpoint of maintenance.
Then, if the actuation temperature for the temperature element is set to a higher level so as to prevent such accident, the above alarm error can be prevented but a new problem arise that the alarm unit is not actuated until the clogging in the condenser becomes heavy. When the alarm unit is not actuated even when the clogging in the condenser proceeds to a substantial degree, troubles such as lowering of freezing power and deterioration of the compressor parts occur.
Further, when the environmental temperature drops such as in winter, not only the temperature of the entire freezing system but also that of the water supplied from the external water supply system drop. In this case, even if there is a substantial degree of clogging in the condenser, the temperature of the cooling medium on the discharge side of the condenser drops below the actuation temperature of the temperature element. In other words, in spite of the lowered freezing power, the alarm unit is not actuated, disadvantageously.
In addition to the problems described above, the conventional automatic ice making machine having a temperature element on the discharge pipe of the condenser also involves the following problems.
The above alarm unit never gives an alarm since it cannot detect such operational error.
This invention has been proposed in view of the above problems inherent in the conventional automatic ice making machines and to solve them properly, and is directed to provide an automatic ice making machine having an alarm unit which can successfully prevent deterioration of the compressor and waste of power or water, free from alarm error.